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N-heterocyclic carbene

Tìm thấy 12+ kết quả cho từ khóa "N-heterocyclic carbene"

Synthesis, characterization and catalytic properties of cationic N-heterocyclic carbene silver complexes

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Poly(ionic liquid)s-supported N-heterocyclic carbene silver complexes for the cycloaddition of CO2 with epoxides. doi.org/10.1007/s . doi.org/10.1002/cctc.201100430. doi.org/10.1021/acsanm.8b01679. doi.org/10.1002/. doi.org/10.1021/acssuschemeng.7b00103. Catalytic activity of N-heterocyclic carbene silver complexes derived from imidazole ligands. Synthesis and catalytic activity of ferrocenyl-substituted N-heterocyclic carbene silver complexes. doi.org/10.7503/cjcu20130254.

The synthesis, characterization, and catalytic properties of (κ2 − C,N)-palladacycles with N-heterocyclic carbene-based ancillary ligands

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Mononuclear N-heterocyclic carbene-based palladacycles (3a–c) were obtained in the reaction of acetate-bridged dimeric palladacycle, [Pd(µ-OAc)(ppy)] 2 (ppy: 2-phenylpyridine), with a stoichiometric of the NHC precursors according to the Scheme.

The role of N-heterocyclic carbene substituents on ruthenium(II) complexes in the catalytic transfer hydrogenation of acetophenone

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The role of N-heterocyclic carbene substituents on ruthenium(II) complexes in the catalytic transfer hydrogenation of acetophenone. Ru(II)-NHC complexes were tested as catalysts for the transfer hydrogenation of acetophenone, showing modest to high activity in this reaction. The results revealed that efficiencies depend on the substituents of the benzene ring of the benzyl on the N atom of the NHC ring.. The characterization of the complexes was accomplished by analytical and spectral methods..

Synthesis and catalytic activity of ionic palladium N-heterocyclic carbene complexes

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Synthesis and catalytic activity of ionic palladium N -heterocyclic carbene complexes. Abstract: The synthesis of 3 benzimidazole-based ionic Pd(II)-NHC complexes (NHC:N -heterocyclic carbene) is presented. The structures of the complexes are as follows: [NHC-PdBr 3. The ionic palladium(II)-NHC complexes were synthesized in high yields and were fully characterized by nuclear magnetic resonance spectroscopy, X-ray diffraction, LC-MS/MS, and elemental analysis.

Contribution of heterobifunctional ligands to transition metal-catalysed C–C coupling reactions

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On these premises, we developed heterobifunctional ligands bearing one N-heterocyclic carbene donor, capable of creating a very strong bond with the metal centre, and one phosphine donor that possesses different stereoelectronic properties. The synthesis of several phosphine-imidazolium salts, differing by the tether length as well as the imidazolium N-substituent, was thus developed and 1a–d (Figure 2) were obtained in good yields in 3 steps from substituted imidazoles.

Computational and biological studies of novel thiazolyl coumarin derivatives synthesized through Suzuki coupling

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The strong sigma donor N-heterocyclic carbene (NHC) based Pd-PEPPSI family of precatalyst systems have been developed by Prof. Therefore, employing precatalyst Pd-PEPPSI-IPr under otherwise similar conditions resulted in 25% desired product (entry 5). To our delight, when the reaction was performed with more sterically demanding Pd-PEPPSI-IPent catalyst in the presence of K t OBu in toluene, the product 5a was obtained in 95% yield (entry 7).

Synthesis, characterization, and microwave-assisted catalytic activity in Heck, Suzuki, Sonogashira, and Buchwald–Hartwig cross-coupling reactions of novel benzimidazole salts bearing N-phthalimidoethyl and benzyl moieties

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The microwave-assisted catalytic activity of N-heterocyclic carbene com- plexes of palladium was determined, generated in situ from the new benzimidazolium salts in the presence of an appropriate base. The catalytic efficiency of the catalyst system in these four popular reac- tions, namely the Mizoroki–Heck, the Suzuki–Miyaura, the Sonogashira, and the Buchwald–Hartwig reaction, as well as electron-releasing and withdrawing substituent effects on the benzimidazole ligands was discussed..

(NHC)-Pd(II) complexes with hydrophilic nitrogen ligands: catalytic properties in neat water

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Palladium-catalyzed carbon–carbon coupling reactions constitute a category of the most frequently employed organic reactions. 2 These reactions are generally carried out in the presence of various ligands, such as tertiary phosphine, which could stabilize the active palladium intermediates. 3 However, traditional phosphines have some drawbacks and, consequently, N-heterocyclic carbene (NHC)-ligated Pd complexes have also received considerable attention as a class of moisture- and air-stable catalyst

The synthesis of 1,3-dialkyl-4-methylimidazolinium salts and their application in palladium catalyzed Heck coupling reactions

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Thousands of free and metal-coordinated N-heterocyclic carbenes have been reported, but NHCs bearing different groups on the backbone of the carbenes are relatively rare.

Resorcinarene-mono-benzimidazolium salts as NHC ligands for Suzuki–Miyaura cross-couplings catalysts

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Key words: Suzuki–Miyaura reaction, resorcinarene, cavitand, N-heterocyclic carbene, benzimidazolium salt, catalyst.

Synthesis of novel benzimidazole salts and microwave-assisted catalytic activity of in situ generated Pd nanoparticles from a catalyst system consisting of benzimidazol salt, Pd(OAc) 2 , and base in a Suzuki-Miyaura reaction

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Recently, we have also investigated the catalytic activity of some in situ prepared N-heterocyclic carbene-Pd complexes for Suzuki–Miyaura cross coupling reactions under microwave heating. 37,38 Since the nature, size, and electronic properties of the substituent on the nitrogen atom(s) of the benzimidazole may play a crucial role in tuning the catalytic activity, to find more efficient palladium catalysts we have synthesized a series of new benzimidazolium halides, 1–5 (Scheme), containing benzyl

One-pot synthesis of new N -(1-methylpyridin-4(1H)-ylidene)amine ligands for palladium-catalyzed Heck coupling reaction

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These highly electron-donating N -(1-methylpyridin-4(1H ) -ylidene)amine ligands considerably improve the catalytic activity of palladium acetate towards Heck–Mizoroki carbon–carbon cross-coupling reactions.. Phosphines and N-heterocyclic carbenes (NHCs) have gained an enormous reputation in the homogeneous cat- alytic world owing to their extensive utility in chemical transformations.

N -functionalized benzimidazol-2-ylidene silver complexes: synthesis, characterization, and antimicrobial studies

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Abstract: 2-Methoxyethyl, 2-diethylaminoethyl, and 2-phenylethyl-substituted N -heterocyclic carbene (NHC) precur- sors were treated with Ag 2 CO 3 to yield silver(I)-NHC complexes (1a–g) in dichloromethane as a solvent at room temperature. The 7 new silver-NHC complexes were fully characterized by means of 1 H NMR, 13 C NMR, and ele- mental analysis techniques.

Achieving elusive transformations with organocatalysis: Direct β-carbon activation of saturated carbonyl compounds

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In this short review, we highlight recent developments for direct β -carbon functionalization of saturated carbonyl compounds based on conceptually new methods including oxidative enamine catalysis, N -heterocyclic carbene (NHC)-assisted catalysis, and photoredox catalysis..

Ag(I) complexes of benzimidazol-2-ylidene ligands: a study of catalytic efficiency towards three-component coupling reactions

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Abstract: The N -heterocyclic carbene (NHC)–Ag(I) complexes 3a–c were synthesized from benzimidazolium chlorides (2a–c = NHC.HCl), incorporating benzyl derivatives and a 2-methoxyethyl group (a: 3 N = 2,4,6-trimethylbenzyl. The synthesized NHC–Ag(I) complexes (3a–c) were tested as catalysts for the catalytic three- component coupling reaction of aldehyde, alkyne, and amine to propargylamines in various solvents.

N-Heterocyclic carbene (NHC) palladium(II) complexes bearing chiral oxazoline ligands and their catalytic activities in allylic alkylation reactions

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N, 6.71. H, 6.89;. 3.87 (t, J = 4.4 Hz, 2 H, NCH 2 CH 2 O), 4.83 (t, J = 4.4 Hz, 2 H, NCH 2 CH 2 O), 5.70 (s, 2 H, C H 2 C 6 H 2 (CH 3 ) 3. H, 7.41. H, 7.32;. N, 6.17%. 3.83 (t, J = 4.8 Hz, 2 H, NCH 2 CH 2 O), 4.87 (t, J = 4.8 Hz, 2 H, NCH 2 CH 2 O), 5.30 (s, 2 H, C H 2 C 6 (CH 3 ) 5. H, 5.26.

Umpolung strategy: advances in catalytic C-C bond formations

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Regarding the nucleophilic nature of N -heterocyclic carbenes, they have been enriching the synthetic organic toolbox with various powerful methods, exclusively for the synthesis of C-C bonds. As already mentioned, there are numerous literature precedents for general coupling reactions of acyl anion equivalents generated from N -heterocyclic carbenes with sp 2 electrophiles.

N-heterocyclic carbenes bearing a naphthyl substituent and their metal complexes: synthesis, structure, and application in catalytic transfer hydrogenation

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7.95 (d, 1 H, J = 7.4 Hz, naph.- H 11. 129.2 (naph.-C 15. 128.1 (naph.-C 13. 127.3 (naph.-C 14. 127.1 (naph.-C 10. 122.8 (naph.-C 12. 7.64 (t, 1 H, J = 6.8 Hz, H 8. 7.57 (t, 1 H, J = 6.8 Hz, H 9. 128.9 (naph.-C 14. 128.7 (naph.-C 13. 128.3 (naph.-C 10. 125.5 (naph.-C 11. 7.63 (t,...

Wittig–Horner reagents: powerful tools in the synthesis of 5-and 6-heterocyclic compounds; shedding light on their application in pharmaceutical chemistry

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The main purpose of this review is to represent a survey of the utility of phosphonyl carbanions in the synthesis of 5- and 6-heterocyclic compounds and provide useful and up-to-date data for chemists. OR OR N H. OR OR N P. O OR OR. P OR OR O N.

Synthesis, characterization, biological studies, and molecular modeling of mixed ligand bivalent metal complexes of Schiff bases based on N -aminopyrimidine-2-one/2-thione

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In: The Chemistry of Heterocyclic Compounds